im sorry for u losing a loved one, but the bible (if u belive in it)says "but to write to them to abstain from .... blood"- Acts 15:20
and because witnesses belive in the bible adn God and want to live by the standards of god adn Jesus christ we dont accept blood transfusions. If some man made this law up we would not practice it. Also it is a known fact that not everyblood transfusion is safe. Blood may contain disease that will end up killing the indivual. Things like Aids, hepitatis and other disease can come from tainted blood.